Parasite protein offers new hope for malaria vaccine

LOCKED IN Red blood cells infected with malaria-causing parasites (shown almost completely filling a cell) may avoid imminent destruction if new research pans out. A parasite protein triggers mouse immune systems to trap the parasites inside cells instead of releasing them into the bloodstream.

Tanzanian toddlers may have handed scientists the key to kicking malaria.

By examining blood plasma of two-year-olds exposed to the disease, researchers have discovered a new vaccine target: a protein recognized by the immune systems of malaria-resistant children.

Malaria, which can be especially deadly for kids, develops when mosquito-borne protozoan parasites invade and then burst out of red blood cells to enter the bloodstream. Drugs can treat the disease, but researchers have struggled to develop vaccines.

Malaria researcher Jonathan Kurtis of Brown University in Providence, R.I., and colleagues examined plasma samples and disease histories collected during a 2005 study of 453 Tanzanian youngsters. The team found that kids resistant to malaria make antibodies that can spot a parasite protein and trap marauding protozoa within red blood cells. Imprisoned, the parasites can no longer rampage through the body.

When the team injected the protein into mice, the animals’ immune systems revved up and churned out antibodies. After infection with a particularly lethal parasite strain, mice making the antibodies survived about twice as long as those not vaccinated, Kurtis and colleagues report in the May 23 Science.

The researchers plan to begin a vaccination trial using the protein in monkeys, followed by a study in humans.